The consumption of contaminated food may cause serious illnesses, and traditional methods to detect Escherichia coli are still associated with long waiting times and high costs given the necessity to transport samples to specialized laboratories. There is a need to develop new technologies that allow cheap, fast, and direct monitoring at the site of interest. Thus, in this work, we developed optical immunosensors for the selective detection of E. coli, based on liquid crystal technology, whose molecules can align in different manners depending on the boundary conditions (such as substrates) as well as the environment that they experience. Each glass substrate was functionalized with anti-E. coli antibody using cysteamine as an intermediate, and a vertical alignment was imposed on the liquid crystal molecules by using DMOAP during functionalization. The presence of bacteria disrupts the alignment of the liquid crystal molecules, changing the intensity of light emerging between cross polarizers, measured using a polarized optical microscope and a monochromator. It was possible to detect E. coli in suspensions in the concentration range from 2.8 cells/mL to 2.8×109 cells/mL. Selectivity was also evaluated, and the sensors were used to analyze contaminated water samples. A prototype was developed to allow faster, in-situ, and easier analysis avoiding bulky instruments.

中文翻译：

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使用快速分析工具选择性检测大肠杆菌的液晶免疫传感器


食用受污染的食物可能会导致严重的疾病，而传统的检测方法大肠杆菌由于需要将样本运送到专门实验室，因此仍然需要等待时间长和成本高。需要开发能够在感兴趣的地点进行廉价、快速和直接监测的新技术。因此，在这项工作中，我们开发了光学免疫传感器，用于选择性检测大肠杆菌，基于液晶技术，其分子可以根据边界条件（例如基板）以及它们所经历的环境以不同的方式排列。每个玻璃基板都经过抗功能化处理大肠杆菌使用半胱胺作为中间体制备抗体，并在功能化过程中使用DMOAP对液晶分子施加垂直取向。细菌的存在破坏了液晶分子的排列，改变了交叉偏振器之间出现的光强度，这是使用偏光光学显微镜和单色仪测量的。原来可以检测到大肠杆菌悬浮液浓度范围为 2.8 个细胞/mL 至 2.8×10 9细胞/毫升。还评估了选择性，并使用传感器来分析受污染的水样。开发了原型以允许更快、原位，并且更容易进行分析，避免使用笨重的仪器。